Laguna_Dude

So I was finally able to take my RS to Thermal for the first time yesterday. I was not able to get fully comfortable in the car; as the active rear steering kept causing me issues. In short, it would interfere while modulating the throttle to balance and control the car in fast sweeping turns and in high speed chicanes.

In a normal car, one can gently modulate the gas to shift weight to deal with under and oversteer. In the RS.. i kept having issues where I would gently modulate gas to shift weight forward to point the car in for turn; and at exact time the rear steering would kick in and cause a the rear to break loose. when driving at 90% the rear steering is fine; as you don't have to modulate as there is plenty of grip.. but once at the limit it becomes a knifes edge. I had to save the car several times.

The rear steering was a prohibitor for me. I had to change my technique to safely drive the car at speed; and even then it was not nearly as fast (in terms of lap times) as I was able to run in my '15 GT3. I could not modulate the gas as much to control weight transfer; and when i did, it had to be very very slight and smooth; you essentially need either all gas or a constant level of maintenance throttle to keep rear from loosing grip during rear steering event; and thus one needs to mostly rely on the wider front tires to hold when on the gas. The car did have more on-power front grip vs. my '15 GT3. for slower, sharp turns, the car did trail-brake and rotate well; the rear steering did help in those situations.

I am hoping a slight adjustment to setup/sways will fix most of the issue; but if not, I have a decision to make... there is a reason Porsche doesn't put active rear steering in its race cars. I am curious to hear other's thoughts, comments and advice on how to deal with it on track.

Thank you.

MileHigh911

Not in the race cars because it is not allowed. Any mfr would add technology if it helped them win. Maybe you are feeling the PTV+ brake the inside rear wheel?? The active rear steer actually stabilizes the car during high speed corners. At what speed were you hitting these corners? And, as far as I know, GT3 and RS RWS is the same

ieatfishburritos

Thanks for posting. It's early on in rws, I'm hoping answers are found before it becomes a street car only feature.

mqandil

May be you are feeling the PTV applying the brakes as others indicated. Personally I did not find the rear steering to be intrusive at all. During fast sweepers or high speed maneuvers, it does help stabilize the rear, and during low speed corners & hairpin it helps you nail the apex every time. It does take you by surprise the very first time you attempt to tackle a hairpin as it makes it so much easier to hit your apex even if you were off your line and your brain is telling you it is not even possible for you to hit the apex, but then you get used to it and it never crosses your mind again. Really surprised by your observations and wondering if there is something wrong with mechanism, or perhaps something wrong with the torque vectoring.

Few years back I had a bad sensor on my 991 911 4S where the torque vectoring would activate during fast sweepers and I ended up spinning out few times and almost crashed on several occasions. It really interfered with weight transfer and made the back end so unstable during high speed sweepers to the point, I was convinced that car was trying to kill me, until I had few seasoned drivers take few laps in the car and confirmed the same thing. The problem was intermittent and It took forever to get it diagnose and rectified. Hopefully you don't have the same issue. Perhaps you can drive another GT3 or GT3 RS and see if this is only happening in your car. Please keep us posted on this. Mark

Laguna_Dude

Just a side note: ESC was always off; TC was on in some sessions; off in others.

Laguna_Dude

Never use ESC; too intrusive. The sweeper was about 100-110 or so, and the chicane 85-95mph. IMO, taking rear tires at limit of grip and then turning them would not only disrupt the car but may cause tires to exceed their grip; especially if at the same time as someone modulates less gas to help rotate the car towards apex. at 90% it seems a nifty thing; but once on the edge, it seems like an unnecessary disruption; cups go just fine without it; and honestly, i would rather it be less stable but more predictable and controllable vs. some random action applied to the rear tires that feels like oversteer.

I genuinely feel the RS RWS is way more pronounced. I don't recall it being remotely as noticeable in my GT3; i felt it was just enough to help in the slow stuff; but not intrusive once at higher speeds.. never felt i had to change my driving to accommodate it. I am truly hoping a setup change fixes this. kind of bummed right now.

Macca

I recall another recent RS owner (and prior 991 GT3 owner) posting something very similar on these boards a week or two ago. They were having problem with the feel of the RWS as well. May pay to have a look for that post and contact the OP as he may have had the car checked and possibly a solution in hand. It is possible that your system needs re calibrating or was not calibrated properly from the factory?

mqandil

Sorry I did not realize you had a 991 GT3, and that you are familiar with the rear wheel steering. I assumed this was your first experience.
May be the RS is set up a little different or as Mecca stated perhaps it is out of calibration from the factory. It does not hurt to get it checked out just in case. Again thanks for sharing. Mark

MileHigh911

PTV and RWS are always on. No matter what is shut off. The RWS turn with the front wheels when over 70 mph I believe. So, if the first turn of the chicane feels OK, but the second one feels way oversteery, I wonder if your RWS is too slow? Which would leave them opposite of what they are suppose to be at the very first start of the second turn. And even if they eventually catch up, maybe they are too late.

Question for RL: Could one unplug the active RWS? I assume you will get lots of warning lights, but if you could, and you take the same corners with it off, it would be a good comparison. Anyone know if it could be unplugged?

ipse dixit

Perhaps the larger contact patch of the rear tires makes the RWS more pronounced?

mqandil

On the GT3, they change directions at 50 mph but not sure if that is the same point on the RS.

I have not read that anyone has attempted to unplug the electric motors on the RWS. I don't see a visible connector on the actuator where you can plug it, but I am sure there is way to do that. The question is if you are able to unplug the motors, (and you probably have to make sure your steering is dead straight first before attempting this), would the actuator hold that (0) angle under load if the motor is unplugged? There is probably a way through the PCM to fix these motors, since they are controlled by PCM. Would be great if anyone knows the answer. Mark

TRAKCAR

Weird.

Never had any kind of negative effect from RWS?
Just massive front grip and a solid planted rear end at speed, unobtainable with street tires without RWS.

MileHigh911

below 30 mph, they turn opposite the front wheels
30-50 nothing
50+ they turn the same direction as front wheels

***corrected***

skremese

Here's some tech info Porsche included about the GT3 in the tech introduction. I've not found a similar doc for the RS.

Mike in CA

I think you may, at least in part, be confusing MPH with KPH. See page 53 in the post above.